Increase In Light Intensity Research Articles

A test of the gleaner–opportunist trade‐off among photosynthetic traits in cryptophyte algae

AbstractAs photosynthetic producers, phytoplankton form the foundation of aquatic food webs. Understanding the relationships among photosynthetic traits in phytoplankton is essential to revealing how diversification of these traits allows phytoplankton to harvest energy from different light environments. We investigated whether the diversification of 15 species of cryptophytes, a phylum of phytoplankton with diverse light‐capturing pigments, showed evidence of trade‐offs among photosynthetic performance traits as predicted by the gleaner–opportunist resource exploitation framework. We constructed photosynthesis versus irradiance (P–E) curves and rapid light curves (RLCs) to estimate parameters characterizing photosynthetic performance and electron transport rate. We inferred the evolutionary relationships among the 15 species with ultraconserved genomic elements and used a phylogenetically controlled approach to test for trade‐offs. Contrary to our prediction, we observed a positive correlation between maximum photosynthetic rate, Pmax, and P–E , an indicator of a species' sensitivity to increases in light intensity when light is a scarce resource. This result could not be explained by electron transfer traits, which were uncorrelated with photosynthetic rate. Together, our results suggest that ecological diversification of light exploitation in cryptophytes has escaped the constraints of a gleaner–opportunist trade‐off. Photosynthetic trade‐offs may be context‐ or scale‐dependent, thereby only emerging when investigated in situations different from the one used here.

Prefrontal cortex neurons encode ambient light intensity differentially across regions and layers

While light can affect emotional and cognitive processes of the medial prefrontal cortex (mPFC), no light-encoding was hitherto identified in this region. Here, extracellular recordings in awake mice revealed that over half of studied mPFC neurons showed photosensitivity, that was diminished by inhibition of intrinsically photosensitive retinal ganglion cells (ipRGCs), or of the upstream thalamic perihabenular nucleus (PHb). In 15% of mPFC photosensitive neurons, firing rate changed monotonically along light-intensity steps and gradients. These light-intensity-encoding neurons comprised four types, two enhancing and two suppressing their firing rate with increased light intensity. Similar types were identified in the PHb, where they exhibited shorter latency and increased sensitivity. Light suppressed prelimbic activity but boosted infralimbic activity, mirroring the regions’ contrasting roles in fear-conditioning, drug-seeking, and anxiety. We posit that prefrontal photosensitivity represents a substrate of light-susceptible, mPFC-mediated functions, which could be ultimately studied as a therapeutical target in psychiatric and addiction disorders.

Influence of Light Irradiation on the Degradation of Dezocine in Injections.

Dezocine, which is well-known as an analgesic, had about 45% share of the Chinese opioid analgesic market. Since drug products containing impurities could bring serious health consequences, it was important to control the generation of impurities and degradation products in the dezocine product. In this study, two kinds of photodegradation products (i.e., degradation product 1 and degradation product 2) in the dezocine injection were isolated using high-performance liquid chromatography. The possible structures of the photodegradation products were identified using both high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. In addition, the possible generation mechanism showed that degradation product 1 was the oxidation product of dezocine, and degradation product 2 was the coupled dimer of dezocine. Finally, we found that the degradation rate of dezocine increased with the increase in light intensity. Moreover, the degradation of dezocine easily occurred under ultraviolet light in comparison with visible light. A deeper insight into the generation of the photodegradation products in the dezocine injection would directly contribute to the safety of drug therapy based on the dezocine injection by minimizing the degradant/impurity-related adverse effects of drug preparations.

Photosynthetic processes in Antarctic sea ice during the spring melt

AbstractHigh‐latitude oceans experience strong seasonality where low light limits photosynthetic activity most of the year. This limitation is pronounced for algae within and underlying sea ice, and these algae are uniquely acclimated to low light levels. During spring melt, however, light intensity and daylength increase drastically, triggering blooms of ice algae that play important roles in carbon cycling and ecosystem productivity. How the algae acclimate to this dynamic and heterogeneous environment is poorly understood. Here, we measured 14C‐carbon fixation rates, photophysiology, and ribulose 1,5‐bisphosphate carboxylase oxygenase (Rubisco) content of sea‐ice algae in coastal waters near the western Antarctic Peninsula during spring, ranging from a low‐light‐acclimated, bottom community to a light‐saturated bloom. Carbon fixation rates by sea‐ice algae were similar to other Antarctic sea‐ice measurements (2–49 mg C m−2 d−1), and there was little phytoplankton biomass in the underlying water at the time of sampling. Net‐to‐gross ratios of carbon fixation were generally high and showed no relationship with ice type. We found algal photophysiology and Rubisco concentrations varied in relation to the different types of ice, altering the balance between the photochemical and biochemical processes that constrain carbon fixation rates. For algae inhabiting the bottom layers of sea ice, rates of carbon fixation were largely constrained by light availability whereas in surface seawater, interior and rotten/brash ice, carbon fixation rates could be calculated with reasonable accuracy from measurements of Rubisco concentrations. This work provides additional insight and means to evaluate carbon fixation rates as sea ice continues to change in future.

Modeling Growth and Photoadaptation of Porphyridium purpureum Batch Culture

The work focuses on mathematical modeling of linear growth marine red algae Porphyridium purpureum batch culture under various surface irradiation. Before starting the batch culture P. purpureum was maintained for 3–5 days in turbidostat, which allowed the culture to adapt to a given light intensity. On each batch curve the maximum specific growth rate and maximum productivity are determined by approximating the exponential and linear growth phases with the appropriate equations. It is taken into account that at the beginning of the linear growth phase the integral light absorption coefficient, calculated from the true absorption spectrum in PAR range, exceeded 50 %. It is shown that with light intensity increase from 15 to 227 µmol photons m–2·s–1 the maximum specific growth rate increased from 0.31 to 1 day–1, the maximum productivity increased from 1.32 to 16.38 g DW m–2·day–1. Mathematical modeling of the linear growth of P. purpureum batch culture have showed that at any light intensity the specific growth rate is determined by the surface illumination, the light absorption coefficient and chlorophyll a concentration. The concept of reduced irradiation – the amount of absorbed light energy per chlorophyll a – was introduced. A linear dependence of the specific growth rate on reduced irradiation is given. The tangent of the angle of line slope is determined by the organization of the key multi-enzyme complex («metabolism bottleneck»). Parameters of this complex depend on the cells photoadaptation degree. For the first time a quantitative relationship between multi-enzyme complex parameters, light intensity and the chlorophyll / P700 ratio was established.

Supplemental greenhouse lighting increased the water use efficiency, crop growth, and cutting production in Cannabis sativa.

The expanding cannabis production sector faces economic challenges, intensified by freshwater scarcity in the main US production areas. Greenhouse cultivation harnesses sunlight to reduce production costs, yet the impact of greenhouse light levels on crucial production components, such as plant growth, branching, and water use efficiency (WUE), remains poorly understood. This study aimed to assess the effects of combined sunlight and supplemental lighting on the crop's main production components and leaf gas exchange of Cannabis sativa 'Suver Haze' in the vegetative stage. Within a greenhouse, LED lighting provided at intensities of ~150, 300, 500, and 700 µmol m-2 s-1 (18-hour photoperiod), combined with solar radiation, resulted in average daily light integrals of 17.9, 29.8, 39.5, and 51.8mol m-2 d-1. Increasing light levels linearly increased biomass, leaf area, and the number of branches per plant and square meter, with respective rates of 0.26g, 32.5 cm2, and 0.41 branches per mole of additional light. As anticipated, crop evapotranspiration increased by 1.8-fold with the increase in light intensity yet crop WUE improved by 1.6-fold when comparing the lowest and highest light treatments. Moreover, water requirements per unit of plant biomass decreased from 0.37 to 0.24 liters per gram when lighting increased from ~18 to 52mol m-2 d-1, marking a 35% reduction in evapotranspiration. These results were supported by increments in leaf photosynthesis and WUE with light enhancement. Furthermore, our findings indicate that even 52mol m-2 d-1 of supplemental lighting did not saturate any of the crop responses to light and can be economically viable for cannabis nurseries. In conclusion, light supplementation strongly enhanced photosynthesis and plant growth while increasing WUE. Additionally, a comprehensive discussion highlights the shared physiological mechanisms governing WUE in diverse plant species and their potential for water conservation under enhanced lighting conditions.

Influence of linearly polarized light on the transverse relaxation of ground-state 133Cs atoms

In order to obtain an understanding of the relationship between the optical absorption and the transverse relaxation, the influences of linearly polarized light respectively at 133Cs D1 and D2 lines on the transverse relaxation of ground-state 133Cs atoms are studied. Under different vapor temperatures, light intensities and light frequencies, transverse spin relaxation times are separately measured for 133Cs atoms in different hyperfine levels. For theoretically analyzing the measuring results, especially for an unusual trend that the transverse spin relaxation time rises with the increase of light intensity, photon absorption cross-sections of linearly polarized light by 133Cs atoms are simulated. The experimental results show that through influencing the optical absorption and spin-exchange collisions, the linearly polarized light plays a remarkable role in the transverse spin relaxation. The results obtained by this paper can provide a guide to find the optimal intensity and frequency of linearly polarized light in practical applications for decreasing the influences of linearly polarized light on the transverse relaxation.

Significantly enhanced photo response of hydrazine hydrate reduced graphene oxide films modified with swift heavy ion irradiation of silver (Ag8+) ions

In this paper, a multistep reduction process of graphene oxide (GO) is discussed. It is basically a two-step reduction process. In the first step, the GO sample is reduced by hydrazine hydrate. In the second step, it is further reduced by a swift heavy ion irradiation beam of silver (Ag8+) ions of 100 MeV energies. Ion beam irradiation causes defects in the hydrazine hydrate reduced graphene oxide (rGO) samples. FTIR study confirms the removal of oxygen containing functional groups. The pore volume and pore density of the samples seem to increase with increase in the ion irradiation doses. It is also seen that the electrical conductivity and specific surface area increases with dose of ion irradiation. The prepared samples were tested for photo response measurement and among all the sample, R5 had the highest photo response of 6.25 % at 30 mW/cm2. The photodetection response seems to increase with increase in intensity of light.

Fiscal decentralization, leader localization, and reduction of pollution and carbon emissions —empirical evidence from China's fiscal “province-managing-county” reform

The fiscal system plays an important role in the government's environmental governance efforts. There is currently no consensus on how fiscal structure adjustments impact pollution and carbon reduction. This paper uses China's fiscal “province-managing-county” reform (FPMCR) implemented in 2004 as a quasi-natural experiment, utilizing panel data from 1670 counties in China from 2000 to 2020 to investigate the impact of fiscal decentralization on reduction pollution and carbon emissions (RPCE), as well as its underlying mechanisms. The results show that (1) from 2000 to 2020, China's RPCE shows an overall trend of fluctuating increase, with its value turning positive after 2013. China's RPCE exhibits a spatial pattern characterized by “lower in the north, higher in the south; higher in the east, lower in the west”. (2) After implementing FPMCR, the RPCE levels in reformed counties decreased by −1.44%, showing that reformed county-level governments prioritize economic development over environmental protection. (3) The mechanism analysis found that after implementing FPMCR, reformed counties experienced a 9.16% increase in nighttime light intensity (NLI), and a 3.99% and 4.34% increase in the number of large-scale industrial enterprises (NLIE) and industrial agglomeration (IA), respectively. This suggests that FPMCR leads to radical urbanization and rapid industrialization in counties, which is detrimental to the improvement of RPCE levels. (4) The spatial heterogeneity analysis found that FPMCR's impact coefficient on RPCE levels in the eastern regions is −1.96%, while in the western regions it is −1.16%. This indicates that reformed counties in the eastern regions are more likely to invest expanded fiscal resources in economic development projects, leading to a decrease in RPCE levels. (5) The temporal heterogeneity analysis found that after the promulgation of the “Three-Year Action Plan to Win the Blue Sky Defense Battle” in 2018, the adverse impact of FPMCR on RPCE is completely reversed, leading to a 1.76% increase in RPCE levels. (6) Further analysis reveals that localizing leaders can slow down the promotion of county-level urbanization and industrialization by the FPMCR, benefiting the improvement of RPCE levels. In other words, “the outsider monk will not recite scriptures as well as a local one”. This study has clarified the causal relationship and underlying mechanisms between fiscal decentralization and environmental governance, providing reliable theoretical support for optimizing grassroots fiscal systems and reducing environmental pollution in other transitional economies. It enriches the field of environmental economics related to fiscal decentralization.

Reactive oxygen species act as the key signaling molecules mediating light-induced anthocyanin biosynthesis in Eucalyptus

Light plays a pivotal role in regulating anthocyanin biosynthesis in plants, and the early light-responsive signals that initiate anthocyanin biosynthesis remain to be elucidated. In this study, we showed that the anthocyanin biosynthesis in Eucalyptus is hypersensitive to increased light intensity. The combined transcriptomic and metabolomic analyses were conducted on Eucalyptus leaves after moderate (ML; 100 μmol m−2 s−1) and high (HL; 300 μmol m−2 s−1) light intensity treatments. The results identified 1940, 1096, 1173, and 2756 differentially expressed genes at 6, 12, 24, and 36 h after HL treatment, respectively. The metabolomic results revealed the primary anthocyanin types, and other differentially accumulated flavonoids and phenylpropane intermediates that were produced in response to HL, which well aligned with the transcriptome results. Moreover, biochemical analysis showed that HL inhibited peroxidase activity and increased the ROS level in Eucalyptus leaves. ROS depletion through co-application of the antioxidants rutin, uric acid, and melatonin significantly reduced, and even abolished, anthocyanin biosynthesis induced by HL treatment. Additionally, exogenous application of hydrogen peroxide efficiently induced anthocyanin biosynthesis within 24 h, even under ML conditions, suggesting that ROS played a major role in activating anthocyanin biosynthesis. A HL-responsive MYB transcription factor EgrMYB113 was identified to play an important role in regulating anthocyanin biosynthesis by targeting multiple anthocyanin biosynthesis genes. Additionally, the results demonstrated that gibberellic acid and sugar signaling contributed to HL-induced anthocyanin biosynthesis. Conclusively, these results suggested that HL triggers multiple signaling pathways to induce anthocyanin biosynthesis, with ROS acting as indispensable mediators in Eucalyptus.

A growth phase analysis on the influence of light intensity on microalgal stress and potential biofuel production

It is urgent to find alternatives to fossil fuels to mitigate the effects of climate change. High light intensity during microalgal growth can promote lipid and carbohydrate accumulation (feedstocks to biofuels). However, more research needs to be done concerning the effect of this factor on microalgal productivity and biochemical composition from a growth phase point of view. This study evaluated the impact of high light intensities (291, 527 and 1107 μmol m−2 s−1) on Chlorella vulgaris growth in synthetic wastewater, nutrient assimilation and biochemical composition in late-exponential and stationary growth phases. Under the highest light intensity, a higher growth rate (0.54 ± 0.02 d−1) and maximum productivity (166 ± 13 mg/L d−1) were achieved. Also, nutrient removal efficiencies at the late-exponential phase reached 97.0 ± 0.2 % and 98.2 ± 0.1 % for nitrogen and phosphorus, respectively. Under all light intensities tested at the stationary phase, microalgae also achieved high nutrient removal efficiencies (>95 %). Extreme light intensity (1107 μmol m−2 s−1) boosted the accumulation of carbohydrates (30 ± 3 % w/w) and lipids (13.0 ± 0.4 % w/w). Under lower light intensities, the content of these compounds did not change significantly between growth phases. The chlorophyll content decreased with the increasing light intensity and increasing exposure time. Exposing C. vulgaris to high light intensity seems promising to simultaneously treat wastewater and boost lipid and carbohydrate accumulation, which can be used for biofuel production.

Optically controlled variable damping system based on PLZT ceramic/ERF in rectangular microchannel

Variable damping control technology based on intelligent materials of electromagnetic excitation has been widely used in the field of (semi-) active vibration control and fluid control. Unfortunately, a major drawback is the electromagnetic noise interference and low response speed. In this paper, a new optically controlled variable damping system based on PLZT ceramic/electrorheological fluid (ERF) is proposed. The mathematical models of the photovoltage generated by PLZT ceramics and the pressure difference between the two ends of the microchannel are established and verified by numerical simulation in COMSOL Multiphysics. Meanwhile, with the increase of light intensity, liquid flow rate and decrease of microchannel height and width, the pressure difference shows an uptrend. Optically controlled variable damping system based on PLZT ceramic/ERF is a control method with the advantages of a clean excitation source, remote control, no electromagnetic interference, and fast response speed, and has a good application prospect in the field of vibration control and fluid control.

Using the urban environment for conservation of rare understory shrub species Daphne jejudoensis and Maesa japonica

To investigate the potential for urban environments on Jeju Island, South Korea, to support the conservation of rare understory shrub species, specifically Daphne jejudoensis and Maesa japonica with limited habitat availability, several study sites were selected to assess the performance of these plants after transplanting. A study site similar to the original habitat (Fo), sites between building gaps (GapJ and GapC), a flowerbed in front of a building (FbJ), the rooftop of a building (Roof), and indoor terraces at higher latitude areas (TeSD and TeSM) were selected. Building gap sites and terrace sites displayed similar but a little lower canopy coverage to the forest site (80−90 %). The flowerbed site showed ∼ 50 % coverage, and the Roof site showed ∼ 30 % canopy coverage. Therefore, urban environmental sites (GapJ, GapC, TeSD, and TeSM) displayed similar canopy coverage to original habitats of D. jejudoensis and M. japonica, with stronger light intensity than the Fo site. Shortwave radiation energy from the sky hemisphere at urban environmental sites was only 15−50 % that of the Roof site and only 3 % that of the Fo site. Therefore, urban environmental sites displayed intermediate radiation between canopy open areas and forest sites. This increased light intensity and radiation led to significantly better performance for both shrub species in terms of photosynthetic rate, water use efficiency, and chlorophyll content at urban environmental sites compared with canopy-opened Roof sites. Furthermore, these sites supported similar plant growth for D. jejudoensis and better growth for M. japonica compared with the Fo site. Therefore, urban environments possess huge potential for successful conservation of rare tree species with limited habitat range. Additionally, results for terrace sites suggest that D. jejudoensis and M. japonica have great potential as indoor gardening plants, which could support species conservation through public engagement. As a pioneering study, our findings highlight the great potential for species conservation using stable and accessible urban environments around buildings.

Amber LEDs outperform red, blue, and red-blue-amber LEDs for lettuce

ABSTRACT Debate persists on light in controlled environment agriculture. To dissect the effects of conventionally used wavelengths on a crop and provide new information to this expanding food production sector, this study investigated the effects of monochromatic and combined red, blue, and amber light on lettuce growth with increasing light intensities (up to 1300 µmol·m−2·sec−1) for 18 days with a 16 h·d−1. Under amber light at PPFDs ranging from 500 to 700 µmol·m−2·sec−1, fresh mass displayed a 33.3% greater yield when compared to red light at the same PPFD. Suppressed growth was observed with either red or amber alone at high PPFD (>800 µmol·m−2·sec−1). Blue light was the least productive of the four treatments, yet lettuce plant growth was not suppressed at high intensities. No growth suppression was observed for lettuce plants grown under combined red-blue-amber light at high intensities, and these plants exhibited greater biomass yield than blue light alone. Varied degrees of pigmentation occurred under each light treatment, yet bleaching was only observed in plants grown under amber light alone at PPFD above 1000 µmol·m−2·sec−1. Findings present novel plant responses to high intensity light, setting precedence for future experiments aimed at expanding the use of LEDs in horticulture.

Physiological and Structural Changes in Leaves of Platycrater arguta Seedlings Exposed to Increasing Light Intensities.

Understanding the light adaptation of plants is critical for conservation. Platycrater arguta, an endangered deciduous shrub endemic to East Asia, possesses high ornamental and phylogeographic value. However, the weak environmental adaptability of P. arguta species has limited its general growth and conservation. To obtain a deeper understanding of the P. arguta growth conditions, we examined the leaf morphology and physiology via anatomical and chloroplast ultrastructural analyses following exposure to different natural light intensities (full light, 40%, and 10%). The findings indicated that P. arguta seedings in the 10% light intensity had significantly improved leaf morphological characteristics and specific leaf area compared to those exposed to other intensities. The net photosynthetic rate, chlorophyll (Chl) content, photosynthetic nitrogen use efficiency (PNUE), and photosynthetic phosphorus use efficiency (PPUE) exhibited marked increases at a 10% light intensity compared to both 40% light and full light intensities, whereas the light compensation point and dark respiration levels reached their lowest values under the 10% light condition. With reduced light, leaf thickness, palisade tissue, spongy tissue, and stomatal density significantly decreased, whereas the stomatal length, stomatal width, and stomatal aperture were significantly elevated. When exposed to 10% light intensity, the ultrastructure of chloroplasts was well developed, chloroplasts and starch grain size, the number of grana, and thylakoids all increased significantly, while the number of plastoglobules was significantly reduced. Relative distance phenotypic plasticity index analysis exhibited that P. arguta adapts to varying light environments predominantly by adjusting PPUE, Chl b, PNUE, chloroplast area, and the activity of PSII reaction centers. We proposed that P. arguta efficiently utilizes low light to reconfigure its energy metabolism by regulating its leaf structure, photosynthetic capacity, nutrient use efficiency, and chloroplast development.

Mutations alter pll gene promoter from constitutive to inducible, coffering palmately lobed leaf trait of melon

The leaves of the common melon are approximately round and uncut. A natural mutant of melon named bm7, which has palmately-lobed leaves. We found that bm7 plants were more conducive to increasing planting density and achieving higher yields, and showed better disease resistance. Therefore, the germplasm resources of muskmelon split leaves have the potential of application. Previous study showed that the palmately-lobed leaf trait was controlled by a single recessive gene, pll (numbered MELO3C010784). By cloning and sequencing the pll genes of Jiashi (wide-type) and bm7 (mutant) plants, we noticed that there was no mutation in this gene, but its expression level in bm7 was far below than that in Jiashi. The silencing of pll gene with virus induced gene silencing (VIGS) confers palmately-lobed leaf trait of Jiashi plants. We found three mutations in the pll gene promoter of bm7 plants, located at 373, 493, 506 bp upstream the translation initiation codon. Then, we had found the pll gene promoter activity of bm7 was significantly lower than that of Jiashi. In addition, the expression level and promoter activity of pll gene in Jiashi plants were not affected by environmental factors, but in bm7 plants, the expression level and promoter activity of pll gene, all decreased with the increase in light intensity and/or temperature. All the results indicated that the mutations convert the pll gene promoter from constitutive to inducible, and results in significantly reduced expression of pll gene, conferring the palmately-lobed leaf trait of melon.

Light Intensity: A Key Ecological Factor in Determining the Growth of Pseudolarix amabilis Seedlings

The notable absence of juvenile Pseudolarix amabilis trees in forest understories suggests their vulnerability to ecological niche competition, leading to limited survival prospects. This study examines the key factors limiting the growth of P. amabilis seedlings by investigating the effects of five ecological factors: light intensity, rainfall, groundwater level, soil type, and type of fertilization, on the growth of one-year-old P. amabilis seedlings. Our results demonstrate that increasing the light intensity promotes plant growth by augmenting the leaf count, leaf biomass, plant height, stem biomass, root biomass, and total biomass. Further analysis reveals that increased light intensity influences biomass allocation, reducing the specific leaf area and leaf–stem biomass ratio, and favoring root and stem growth over leaf investment. Rainfall, groundwater level, fertilization type, and rhizosphere soil type primarily influence root growth by impacting the soil’s physicochemical properties. Specifically, rising groundwater levels lower the soil temperature and increase the soil moisture, total potassium content, and soil pH, leading to reductions in root biomass, plant height, net height increment, leaf number, and total biomass. When groundwater levels reach 21 cm and 28 cm, submerging the surface soil layer, root biomass decreases by 1.6 g/plant (−51.6%) and 2.3 g/plant (−74.2%), respectively. Further analysis reveals a gradual decrease in the root–shoot ratio above the 14 cm groundwater level, while the specific leaf area and leaf–stem biomass ratio remains unaffected, indicating stronger belowground root stress compared to aboveground stem and leaf components. The results highlight light intensity as the key ecological factor determining the growth of P. amabilis seedlings. These findings underscore the importance of considering light intensity in the management of natural stands, the cultivation of artificial forests, and the nursery cultivation of endangered P. amabilis.

Modified Uni-Traveling-Carrier Photodetector with Its Optimized Cliff Layer.

We have designed the MUTC-PD with an optimized thickness of cliff layer to pre-distort the electric field at the front side of the collection layer. With the optimized MUTC-PD design, the collapse of the electric field will be greatly suppressed, and the electrons in its collection layer will gradually reach their peak velocity with the growing incident light power. Moreover, as the incident light intensity increases, the differential capacitance also declines, thus the total bandwidth grows. It will make the MUTC-PD achieve high-speed and high-power response performance simultaneously. Based on simulation, for 16μm MUTC-PD with a 70 nm cliff layer, the maximum 3 dB bandwidth at -5 V is 137 GHz, compared with 64 GHz for the MUTC-PD with a 30 nm cliff layer. The saturation RF output power is 27.4 dBm at 60 GHz.

Differential stability of bacterial photosynthetic apparatus of Rhodobacter alkalitolerans strain JA916T under alkaline and light environment.

In purple bacteria, photosynthesis is performed by densely packed pigment-protein complexes, including the light-harvesting complexes known as RC-LH1 and LH2, with carotenoids to assist in the functioning of photosynthesis. Most photosynthetic bacteria are exposed to various abiotic stresses such as light, temperature, alkalinity-acidity, and salinity. Rhodobacter (R.) alkalitolerans was discovered from the alkaline pond; here, we report the comparative study of the photosynthetic apparatus of R. alkalitolerans in various light intensities in relation to its high pH tolerance ability. With increased light intensity, the stability of photosystem complexes decreased in normal pH (npH pH 6.80 ± 0.05) conditions, whereas in high pH (hpH pH 8.60 ± 0.05), acclimation was observed to high light. The content of bacteriochlorophyll a, absorbance spectra, and circular dichroism data shows that the integrity of photosystem complexes is less affected in hpH compared with npH conditions. Large pore blue native polyacrylamide gel electrophoresis of photosystem protein complexes and sucrose density gradient of n-dodecyl β-D-maltoside solubilized intracytoplasmic membranes show that LH2 is more affected in npH than in hpH, whereas RC-LH1 monomer or dimer has shown interplay between monomer and dimer in hpH, although the dimer and monomer both increased in npH. Increased content and expression level of ATPase protein complex and subunit-"c" of ATPase, fast relaxation kinetics of p515, and relatively higher membrane lipid content in hpH along with less photooxidative stress and subsequently lesser superoxide dismutase activity exemplify photoprotection in hpH. Furthermore, the increased expression levels of antiporter NhaD in hpH signify its role in the maintenance of homeostatic balance in hpH.

Natural history and biomarkers of KCNV2-associated retinopathy.

KCNV2-associated retinopathy is an autosomal recessive inherited retinal disease classically named cone dystrophy with supernormal rod response (CDSRR). This study aims to identify the best biomarker for evaluating the condition. A retrospective review of eight patients from seven families with genetically confirmed KCNV2-associated retinopathy was performed. The best corrected visual acuity (BCVA), full-field electroretinogram (ffERG), pattern ERG (pERG), fundus imaging: retinal photograph and fundus autofluorescence (FAF), and optical coherence tomography (OCT) were analysed. There was a disproportionate increase in b-wave amplitude with a relatively small light intensity increase, especially between the two dimmest stimuli of DA 0.002 and 0.01 (-2.7 and -2.0 log cd.s/m2). The a-wave amplitude was normal. The a-wave peak time was delayed in all stimuli. The b-wave peak time was delayed compared to normal, but the gap tightened as intensity increased. The b:a wave ratio was above or at the upper limit for the reference values. FAF bull's eye maculopathy pattern was prominent and variable foveal disruption on OCT was apparent in all patients. Legal blindness was reached before the age of 25. We identified three potential electrophysiology biomarkers to assist in evaluating future therapies: the disproportionate b-wave amplitude jump, delayed a-wave and b-wave peak time, and the higher than normal b:a wave ratio. Any of these biomarkers found with photoreceptor ellipsoid zone foveal-perifoveal disruption should prompt consideration for KCNV2 retinopathy. The BCVA natural history data suggests the probable optimum therapeutic window in the first three decades of life.